In recent years, images being obtained with image diagnostic apparatuses such as X-ray, X-ray CT or MRI have been widely used, not only at the time of diagnosis, but also at the time of treatment. There has especially been an increase in studies for extracting automatically a specified organ out of display images for the purpose of diagnosis or treatment. For example, displaying the coronary artery pattern running in the vicinity of cardiac surface in 3-dimensional representation would be extremely useful at clinical sites.
However, in the case of segmenting the organ regions or extracting the specified regions, there is still a need for doctors to rely on their anatomical knowledge for diagnosis and recognition. Particularly, in the case of identifying an organ region, a method to approximate a simple graphic to a contour of the organ according to the anatomical knowledge of an organ to be identified is implemented. For example, as disclosed in Patent Document 1, on an ultrasonic diagnostic image, the internal volume of the left ventricle of a heart is obtained by approximating an ellipse to the contour of a left ventricle and by determining the left ventricle region.
However, the shapes of organs are generally quite complicated, thus making it difficult to precisely approximate the contours of them using a simple graphic in all cases. Approximation with a simple graphic will surely cause some errors, and the operation for the approximation would be repetitive and complicated work.
Also, the method being disclosed in Patent Document 1 relates to an elliptical internal region, and it causes a problem in the case of extracting a coronary artery located in the cardiac surface region using MIP (Maximum Intensity Projection) processing, because there are occasions upon attempting MIP processing by specifying the region encompassing the heart including the surface region that the coronary artery becomes invisible due to the high signal region of the cardiac internal region being projected.
Patent Document 1: JP-A-2000-210284